The present invention relates to heat exchanger assemblies, and more particularly to a method and apparatus for separating sections of thin-walled multiport micro-extrusions to provide micro-tubes for use in heat exchanger assemblies.
In order to produce heat exchanger assemblies that are of extremely high efficiency, lightweight and economical, heat exchanger assemblies are being produced which employ a thin-walled multiport condenser tube. The small condenser tube, hereinafter referred to as a micro-tube, is a very small oval tube approximately one-half inch to one inch in width and 0.050 inches to 0.100 inches in thickness and having a multitude of minute ports, typically ten to twenty in number within the tube. The condenser tube is formed using an extrusion process which provides a micro-extrusion typically a hundred feet or more in length. The micro-extrusion is cut into sections of usable length, typically twenty to thirty inches long. A plurality of such micro-tubes are assembled together with a suitable heat transfer array such as, for example, folded fin units, which are positioned between parallel passes of the micro-tubes. Such heat exchanger assemblies provide a condenser of extremely high efficiency while being extremely lightweight and economical in the use of material.
The use of the micro-tubes as a condenser tube in a heat exchanger assembly has mandated that the micro-tube be made as an extrusion, preferably of aluminum. In such an extrusion, preferably of aluminum, the micro-tube with its minute ports is produced from a solid billet and the ports are formed from solid material. In the extrusion process, the inside of the micro-tube and its ports are completely devoid of any contamination.
Known arrangements for providing such micro-tubes in the desired pass lengths involves the use of saw cutting to cut extruded lengths of thin-walled multiport tubing to the desired lengths. A major problem with such separation method is that metal cuttings, or particles, and cutting lubricants penetrate the openings, or ports in the tubing, plugging the openings. Because of the microscopic size of the individual ports, it is an extremely difficult task to remove such contamination from the ports. Due to the end use of the product, namely a refrigeration condenser or heat exchanger, it is essential that no foreign matter enter the heat exchanger during its fabrication.
It would therefore be highly desirable to have a method and apparatus for parting extruded, extremely thin-walled multiport micro-tubes into single predetermined lengths, without the use of saws to cut tubular stock to sections of the desired lengths, cutting lubricants, or other conventional means which require breaching the ports during the separation process.